Picnic baskets have become increasingly useful by the relatively recent advent of the use of rigid foam plastic for insulation purposes. These picnic coolers typically are of rigid foamed polystyrene, and consist of a body, a lid and carrying handles applied to the body portion. Handles of the rigid foam cannot be made because the foam has insufficient strength. Further, the foam, while rigid, is soft and crumbles relatively easily in normal use.
More recently, picnic coolers have employed a double-wall construction of a blow-molded plastic in which insulation is placed. The insulation may be foamed in place and typically is of urethane composition. The outer plastic shell may be a polyolefin, such as polystyrene, polyethylene, polypropylene, an ABS resin or any other suitable type. Coolers of this construction are of better quality than the non-sheathed rigid foam type, but are considerably more expensive and difficult to construct.
Further, end-mounted handles for all types of coolers are of two basic types, short and long, and give rise to two problems. Short handles mounted on externally projecting brackets fold up parallel to and contact the side walls of the container on which they are mounted. When the cooler is carried loaded, the weight forces the hands of the person carrying the cooler into the side walls. If the cooler is of the rigid but soft foam type, the cooler as well as the knuckles of the person may be damaged. Where the cooler is of the hard, rigid external shell type, the knuckles of the person may be bruised; the cooler cannot be carried far or conveniently.
Long, side-mounted handles overcome the above problem as they extend above the surface of the lid of the cooler. However, in the down position the handles may extend below the bottom surface of the cooler. The handles must be stored at an angle to the side, and thus take more room. Further, the long handles cannot be used as lid props.